This invention relates to means for rapidly determining the effectiveness of cancer therapy, and to means for augmenting such therapy through the use of antibodies to necrotic or damaged neoplastic tissue that are conjugated to labels or pharmaceutically active molecules.
Modern techniques for the nonsurgical treatment of cancer include both clinical and experimental techniques involving chemotherapy, radiation therapy, a combination of chemotherapy and radiation therapy, and immunotherapy. In each instance, the object of the therapy is to kill the malignant cells. Antineoplastic agents presently or potentially useful in such therapy include cytotoxic drugs, biological response modifiers, radiosensitizing compounds, toxins, and radionuclides.
One difficulty associated with cancer therapy is that the effectiveness of a particular therapy varies significantly from one type of cancer to another type of cancer, and even among patients with the same type of cancer. In fact, even individual neoplasms in a single patient may be heterogeneous, having some cells that are more receptive or resistant than others to the particular therapy being utilized. For these reasons, the selection of an effective cancer therapy regimen for a particular patient having a particular type of cancer is not an exact science, but must, in the final analysis, be determined empirically.
A. Monitoring of Effects of Therapy
It is the patient that suffers as a result of this lack of certitude in the establishment of the optimal treatment regimen. The side effects from chemotherapy and radiation therapy are notorious, and include weight loss, vomiting, hearing impairment, hair loss, gastrointestinal damage, and bone marrow damage. Accordingly, physicians make every effort to monitor the effects of the particular treatment regimen being utilized. If the treatment is ineffective, it is discontinued and an alternative treatment is instituted as soon as is feasible.
Conventional methods for monitoring the effectiveness of chemotherapy, radiation therapy, and other nonsurgical cancer therapy include CAT scans, liver-spleen scans, X-rays, Magnetic Resonance (MR) scans, and manual palpation of the tumor, all to detect reduction in tumor size. These techniques are generally useful only after three to four weeks of therapy, since a substantial reduction in tumor size is required in order to identify changes. The patient is therefore committed to a particular therapeutic regimen (and concomitant side effects) until completion of these diagnostic methods.
A monitoring technique that would permit the clinician to determine in a short period of time the effectiveness of a particular therapy in each particular patient would greatly facilitate attainment of the optimum therapeutic regimen while minimizing the time required to do so. Such a technique would also permit the treating physician to minimize the time in which the patient is subjected to ineffective therapy with its accompanying side effects.
B. Augmentation Therapy
Because of the heterogeneous nature of many neoplasms, and because of the mechanisms by which certain therapeutic measures work, not all the cells in a tumor respond to therapy. With a heterogeneous neoplasm, some, but not all of the cells may be susceptible to a particular chemotherapeutic agent. Additionally, radiation therapy and antiproliferative chemotherapeutic agents primarily injure only rapidly growing cells. At any one time, the number of cells in a growth phase is likely to represent only a small number of the total cell population in a tumor. For these reasons, such therapy often reduces, but does not eliminate, the tumor burden. Accordingly, there is a need in that situation for an effective method for destroying the remaining tumor cells.
C. De Novo Therapy of Neoplasms
Finally, because of the hetereogeneity of different types of neoplasms, many different therapeutic approaches have been utilized, forcing clinician and patient to undergo extensive and expensive clinical, radiologic, and laboratory investigations to determine the tumor type. There is therefore a clear need to develop therapeutic approaches applicable in a more uniform way to a broad spectrum of different types of cancer.
Antibodies, and in particular monoclonal antibodies, are the focus of intense interest in the field of cancer research. Antibodies have been developed to cell-surface antigens for a number of malignancies, but are useful only in restricted categories of tumors. Techniques are known for conjugating such antibodies to pharmacologically active agents or to labels to permit diagnosis, localization, and therapy directed toward such tumors. Such presently-known conjugates again are useful only in restricted categories of tumors.
Recent research has led to the identification of unique nuclear antigens and the development of monoclonal antibodies thereto. See, e.g., A. Epstein and C. Clevenger, Identification of Nuclear Antigens in Human Cells by Immunofluorescence, Immunoelectron Microscopy, and Immunobiochemical Methods Using Monoclonal Antibodies, Progress in Non-Histone Protein Research, 117 et seq. (I. Bekhor ed. 1985); C. Clevenger and A. Epstein, Identification of a Nuclear Protein Component of Interchromatin Granules Using a Monoclonal Antibody and Immunogold Electron Microscopy, Exp. Cell Res. 151: 194-207 (1984); and C. Clevenger and A. Epstein, Use of Immunogold Electron Microscopy and Monoclonal Antibodies in the Identification of Nuclear Substructures, J. Histochem. and Cytochem. 32: 757-765 (1984). Such antibodies have been labeled and have been used to identify structures within the nucleus. Id.
The cardiac protein myosin is well known. This protein is an intracellular muscle protein found inside cardiac cells, but not on the cell wall. Myosin-specific antibodies have been developed and have been labeled for in vivo imaging of heart tissue damaged by myocardial infarction. See G. Beller, B. Khaw, E. Haber and T. Smith, Localization of Radiolabeled Cardiac Myosin-specific Antibody in Myocardial Infarcts, Circulation 55: 74-78 (1977).